Boiler Basics Part 1 – Types and Components
This series of articles is written by senior boiler tech (and all around swell guy) Justin Skinner. Thanks Justin.
Commercial Style Fire tube
Residential style sectional, note flue passes
Water Tube Boiler Design
Whats the difference in application and why use one type over the other?
Water tubes are generally considered safer. They contain much less water than fire tubes, so if a disturbance occurs (tube breaks, boiler melt down) there isn’t as much water/steam to have the potential to escape the boiler.
The main determining factor of water or fire tube is application. Water tubes are able to handle much higher pressure ( 1000s of psi), and fire tubes generally aren’t designed to be used over 350 psi. Water tubes are available in much larger capacities than fire tubes, and are able to recover a lot faster from a large increase in load demand from a pressure stand point. Meaning if the pressure drops on a fire tube boiler, it takes longer to come back up than on a similarly rated water tube boiler. Fire tube boilers typically have lower operating and maintenance costs, have easier access to the fire and water sides for inspections, and its much easier to replace tubes on a fire tube than a water tube. Generally speaking, if you have fluctuating demand and large swings in steam requirements, a water tube is probably a better fit. If you have a pretty constant load requirement without a lot of swing in steam demands, a fire tube would work fine. My next article will cover boiler components and safeties.
Water Tube Boilers